> Having to reboot every time I recompile the module or play with git
> makes modules useless for development :-(.

Confirmed. -rc3 (from 2.6.33 - sorry) was the only kernel I ever
observed this on (I simply changed a driver and redid make modules_install,
boom, version string (/lib/modules/...) changed from 2.6.34-rc3 to
2.6.34-rc3-...-dirty, despite having kept my git unupdated and on the
2.6.34-rc3 tag.